Since the advent of windows in dwellings, man has been attempting to modify heat loss or absorption through these openings and thus conserve energy.
One general category of devices attempting to solve this problem has been the use of draperies. However, draperies have been used predominantly for ornamental purposes and privacy and their energy conservation effects are minimal. Double hung draperies have also been utilized in the past but these devices are relatively clumsy and unattractive and are provided for reasons other than energy conservation. For instance the double hung drapery of Syrett in U.S. Pat. No. 1,424,324 is provided as a dust shield and as such does not incorporate reflective or absorptive surfaces required for energy conservation. E. Roy in U.S. Pat. No. 1,567,196 illustrates a double hung drapery or curtain but fails to suggest that the device encompasses the concept of a drapery liner having thermal or radiation barrier properties. The double hung draperies presented in the prior art have additional drawbacks in that they require special considerations for hanging such as additional rods or hooks and they are not manufactured in a way which will permit their folding in a pattern identical to the associated draperies and thus they detract from the esthetic appeal of the draperies.
Other energy conservation measures have been utilized with respect to windows which includes applying a reflective film directly to the glazing. This approach is satisfactory in eliminating solar radiation from a room and thus minimizes solar heating so that air conditioning of the room may be accomplished in an economical manner. However, that concept also prevents solar heating of the room during the cooler months of the year and thus increases the energy costs for heating the room. The reflective coatings on the glazing also inhibits observation through the windows from the reflective side.